Normal volunteers will receive a standard dose of triazolam either alone or together with one each of low-dose ketoconazole, or high dose ketoconazole, in order to determine an adequate dose of ketoconazole for inhibition of the CYP3A4 enzyme system. Placebo-alone arm is included in the study design. In addition, they will undergo psychometric testing to determine the effects of any, of altered elimination half-life on suggestive effects of triazolam. Serial blood levels and urine samples for pharmacokinetic studies will be collected.